This has happened as we tied blueprints to OS versions via fixed templates so we do have blueprint sprawl with all the available Linux versions out there. The way forward could be selectable templates using vRO code but as I'm running 7.5 do anyone know of another way without the custom code?
SovLabs Property Toolkit is what I see used most often. Allows you to use logic within vRA itself to pick what template you want. Requires no custom vRO code at all. There is also Component Profiles but that is more restricted than the first option.